Ink jet printers contain semiconductor chips which are electrically activated to eject ink droplets on demand through nozzle holes in a nozzle plate attached to the chips. In a “roof shooter” type printhead, ink is provided to the active surface of the chips for ink droplet ejection through ink vias or ink feed slots which are formed through the thickness dimension of the chips. In order to produce printhead chips in large quantities with minimum production costs, grit blasting is conventionally used to blast slots in a silicon wafer prior to dicing the wafer to form individual semiconductor chips. The silicon wafers are typically processed prior to grit blasting to contain insulative, conductive, resistive, passivation and/or cavitation layers which provide the active surface for ink ejection. During the grit blasting process, which is typically conducted from the side of the wafer opposite the active surface, some of the grit passing through the wafer may ricochet and impinge on the active surface side of the wafer thereby causing electrical shorts and open circuits. The shorts or open circuits must be repaired or the chips containing the damaged circuits discarded, these steps resulting in lower product yields and/or lower production rates. There is a need, therefore, for improved methods for grit blasting ink feed vias or slots in silicon wafers used to make ink jet printhead chips.